There is at present a great number of nozzles for the projection and/or injection of any kind of fluids, gases, liquids or mixtures thereof. The main differences relate to the form and size, which characteristics are in turn associated with the properties of the fluid and the necessary volume of flow. The purpose of most devices incorporated into the nozzles is to regulate and/or interrupt the flow, while the objective of others is to properly regulating the mixture in the case of compound fluids.
In the case of projecting viscous fluids, in addition to the pump in charge of causing draining, pressurized air is incorporated into the nozzle, with said nozzle generally being a straight extension of the hose or flexible pipe where the air duct couples in addition to the flow regulating devices and those devices in charge of adjusting the mixture.
Mortars are one of the viscous fluids pumped and projected, mainly to apply stucco, i.e. to provide smooth coating to walls, ceilings and even floors. This procedure is performed with a machine in charge of mixing the mortar—that has been pre-dosed dry—with water and then pumping it through flexible pipe, to which end a nozzle is coupled, which is basically a straight extension of the hose to which another pipe is connected to inject pressurized air. The result is that the mortar is projected to the surface one would like to coat.
An example of a nozzle for injection can be found in the European patent EP 199121 of 1989, entitled “Fluid Injection Apparatus”, where a piston is described that slides within a cylindrical casing to force a fluid provided in a container through the nozzle. The piston is forced with a spring for an automatic discharge with the action being withheld by a spring through a projection coupling in the piston rod.